outdoor landescape low voltage lights

[energizer bunny]

low voltage lighting 12v system 175 foot run of cable starting with 16 gage first 100 feet 18 gage last 75 feet 11 and 12 watt lights total wattage is 86 watts 88 watt transfomer out put last lights are very dim i requier a larger trans correct please advise

 

[don_resqcapt19]

Your wire is way undersized. A #6 would give you about 5% drop at 100' with a 7.16amp load.

 

[Dennis Alwon]

Kim lighting has a small chart for voltage drop. Go to Kim Lighting.
At the bottom choose library catalog. Go to page 92 of 120. Good luck. The PDF is large so it may take a minute to download.

 

[WinZip]

Once you see the price of 8-2 LV cable you might want to split the run an use 2 runs of 10-2

 

[WinZip]

Sorry I meant 2 runs of 12-2

 

[WinZip]

Run #1 - 100 feet 50 watts 12-2 LV cable

Run #2 - 175 feet 40 watts 12-2 LV cable

The above will work

 

[don_resqcapt19]

Run #1 - 100 feet 50 watts 12-2 LV cable

Run #2 - 175 feet 40 watts 12-2 LV cable

The above will work

I show run #1 with 11.6% voltage drop and run #2 with a 16.6% drop. I would expect in both cases the lamps would look dim.

 

[WinZip]

low voltage lighting 12v system 175 foot run of cable starting with 16 gage first 100 feet 18 gage last 75 feet 11 and 12 watt lights total wattage is 86 watts 88 watt transfomer out put last lights are very dim i requier a larger trans correct please advise

When installing LV landscape lighting it can be a difficult task trying to deliver the proper voltage to fixtures , for example lets look at a job that calls for 85 fixtures lamp sizes from 20-50 watt mr 16 total 2500 to 2700 watts.

One of the ways to accomplish what you want would be to place transformers around the property so that you can deliver 11-12v to all fixtures 3 - 300 watt transformers 3 - 600 watt transformers, now comes getting 120v to each transformer mounted on post or in ground transformers along with a pvc switch box - GFCI WR / TP and bubble cover , as you can see this set up is pricey but efficient.

Another way would be to use 3 - 900 watt transformers multi tap 12 to 18v , less electrical to do but more LV cabling and voltage drop to deal with , some runs you may have to push 18v over 100 feet to receive 11-12v to the lighting and as another poster said as lamps happen to burn out the voltage will increase on the other lamps due to delivering the 18v an in time the other lamps on that run will also start to go due to higher voltage present for each lamp that burns out - if the lighting is not maintained.

Another way to get the proper voltage to each fixture 11-12v is a hub or spider splice system where you have calculated the voltage drop to a central hub location / junction point and 5-6 fixtures are fed from this junction point , this system seems to work pretty well from what I have seen.

I am sure most of you have other ideas and different ways to set up a job as listed above and I for one would enjoy reading your comments and post.

WinZip

 

[Volta]

...I am sure most of you have other ideas and different ways to set up a job as listed above and I for one would enjoy reading your comments and post.

WinZip

Sure, bigger wire .

 

[WinZip]

Good idea , ets use 250 MCM 2 conductors around a property some where around 800 feet of each then there are the connections to each fixture , that would be a pleasant work day/month.

 

[LarryFine]

Run #1 - 100 feet 50 watts 12-2 LV cable

Run #2 - 175 feet 40 watts 12-2 LV cable

The above will work

I show run #1 with 11.6% voltage drop and run #2 with a 16.6% drop. I would expect in both cases the lamps would look dim.

What if he groups them 60w and 30w, respectively?

What if he uses #10 for each home run?

 

[WinZip]

A close friend that we do a lot of work for that's in the pool construction an maintenance business has aloud me to set up deck and landscape lighting display withing his 3000 sq foot store and he also wants to do pond an fountain displays which also in tails lighting so this should prove to be an Interesting project for both of us.

WinZip

 

[don_resqcapt19]

What if he groups them 60w and 30w, respectively?

14.2% and 12.6%

What if he uses #10 for each home run?

9.2% and 7.6%

 

[iwire]

14.2% and 12.6%

9.2% and 7.6%

And all of these figures will result in a significant reduction in light output.

 

[broadgage]

Does the NEC limit this type of lighting to 12 volts, or could 24/25 volts be used instead ?
Here in the UK I have used 12 volt lamps in series pairs from a 25 volt transformer. The saving in cable is substantial.

A series pair of 12 volt lamps will draw half the current of a paralel pair, and this permits of 4 times the cable length, not twice as might be expected.
If a 25 volt transformer is used, then the extra volt allows a furthur increase in cable lengths.

Suppose that a maximum of 1 volt drop is accepted, i.e. 12 volts at the transformer and 11 volts at the lamp.
If the lamps are connected in series instead from a 24 volt transformer, then the acceptable voltage drop is 2 volts, to ensure 11 volts at the lamps, this allows four times the run (half current, and 2 volts loss instead of 1)

If a 25 volt transformer was used, then 3 volts may be dropped and still ensure 11 volts at the lamps, that gives 6 times the cable run.

 

[Dennis Alwon]

Does the NEC limit this type of lighting to 12 volts, or could 24/25 volts be used instead ?
Here in the UK I have used 12 volt lamps in series pairs from a 25 volt transformer. The saving in cable is substantial.

We also have 24v light fixtures but for some reason they are not as popular.

 

[WinZip]

Delivering 10.8 to 11.5 volts to a group of mr 16 lamps due to voltage drop is not that noticeable at all , it can be a difficult task to deliver the full 12v to all lamps but there are wiring methods that will work but are more involved.

 

[WinZip]

I'm not pushing cast lighting but this link shows you how to get very close to the proper voltage to a group of 6 fixtures an works very well, each fixture has 25 ft cord attached that goes back to a splice junction.

Midway down the page

http://www.cast-lighting.com/search/1/display-document/24

 

[iwire]

Delivering 10.8 to 11.5 volts to a group of mr 16 lamps due to voltage drop is not that noticeable at all ,

I cannot disagree more strongly, that will be a signicant reduction in light output.

When the actual voltage delivered to a given incandescent lamp is lower than the lamp?s rated voltage, the light output will be reduced. This relationship isn?t linear. When the voltage decreases to about 85% of its rated value, the visible light output is only about 50%. It continues to drop quickly from this point forward.

http://ecmweb.com/news/electric_fundamentals_successful_lowvoltage/

Incandescent lamps are very sensitive to changes in the supply voltage. These characteristics are of great practical and economic importance.

For a supply voltage V near the rated voltage of the lamp:

* Light output is approximately proportional to V 3.4
* Power consumption is approximately proportional to V 1.6
* Lifetime is approximately proportional to V −16
* Color temperature is approximately proportional to V 0.42 [61]

This means that a 5% reduction in operating voltage will more than double the life of the bulb, at the expense of reducing its light output by about 20%.

http://en.wikipedia.org/wiki/Incandescent_light_bulb#Voltage.2C_light_output.2C_and_lifetime

it can be a difficult task to deliver the full 12v to all lamps but there are wiring methods that will work but are more involved.

There is nothing difficult about it, use larger conductors or reduce the distances or reduce the load.

 

[WinZip]

Yes sir Bob larger cabling will work but much more costly.